The present invention relates to wireless transceivers for transmitting and receiving digital data and, in particular, to a transceiver system that varies the effective bit transmission rate within individual data packets or frames.
The connection of electrical devices to the Internet using wireless protocols, for example WiFi, has provided what may be termed “discrete mobility” to users of laptop computers and other devices. With discrete mobility, the user of the device is free to work at a variety of locations but typically suspends use of the device while moving between locations.
In providing discrete mobility, current wireless protocols adapt to different qualities of the wireless transmission link (for example, the amount of electrical interference in the transmission link or the signal strength of the transmission) at different locations by changing the transmission rate of the data packets and providing for retransmission of data packets that are corrupted. Generally, lower transmission rates provide improved transmission over noisy or low signal strength links In the retransmission of corrupted data packets, the corruption may be detected, for example, by error detection codes associated with each packet, or missing packet sequence numbers.
The discrete mobility offered by current wireless protocols is often inadequate for wireless devices such as phones and music players where the user expects “continuous mobility”. Such continuous mobility requires a real-time Internet connection with low latency as the user moves between locations. Yet, measurements made by the present inventors using a mobile phone implementing voice over WiFi (VoWiFi) using standard transmission rate adaptation and retransmission mechanisms found that 80% of the data required retransmission.